Exhaustion is not unique to our overstimulated age.

Anna Katharina Schaffner, author of the book "Exhaustion: A History (2016), does a precis of its arguments,

Is ours the most exhausting age ever?..The argument goes that human energy levels have basically remained static throughout history, while the cognitive, emotional and temporal demands on the modern subject have increased so sharply that a chronic deficit of inner resources ensues...

..anxieties about exhaustion are not peculiar to our age. Those who imagine that life in the past was simpler, slower and better are wrong...exhaustion and its effects have preoccupied thinkers since classical antiquity...Over the centuries, medical, cultural, literary and biographical sources have cast exhaustion as a biochemical imbalance, a somatic ailment, a viral disease and a spiritual failing. It has been linked to loss, the alignment of the planets, a perverse desire for death, and social and economic disruption.

Exhaustion theories often address questions of responsibility, agency and willpower. In some accounts, exhaustion is represented as a form of weakness and lack of willpower, or even as a grave spiritual failing manifest in a bad mental attitude. For instance, medieval theories centred around the notion of acedia and sin, while recent neoliberal theories blame individuals for the management of their physical and mental wellbeing...Acedia literally denotes a ‘state of non-caring’, and has also been described as ‘weariness of the heart’. It primarily affected monks in late antiquity and the early medieval period, and was thought to be the result of a weak spiritual disposition and giving in to demonic temptations.

In Greek antiquity, a surplus of black bile that wreaks havoc with the bodily humoral economy was blamed. In the 19th century, it was a lack of nerve-power, and in the 20th and 21st centuries, a cognitive system chronically overstrained by external stimuli and stressors.

The 19th-century American physician George M Beard invented the neurasthenia diagnosis, a vaguely defined nervous exhaustion, and declared it to be a disease of civilisation, triggered by characteristics of the modern age, including ‘steam-power, the periodical press, the telegraph, the sciences, and the mental activity of women’...A century before Beard, the Scottish physician George Cheyne (1671-1743) already theorised the ‘English Malady’, manifest in a ‘Lowness of Spirits, lethargick Dullness, Melancholy and Moping’, and which he blamed on the fast-growing wealth of the sea-faring English nation and the adverse consequences of immoderation, laziness and luxury lifestyles. Burnout theorists of the 21st century are still making similar arguments about the damaging effects of new communication technologies and the neoliberal workplace.

...the continual production of theories about the loss of human energy is also an expression of timeless anxieties about death, ageing and the dangers of waning engagement. Theorising about exhaustion, and proposing cures and therapeutics for its effects, is a tactic to counteract the awareness of our helplessness in the face of our mortality. It is, in other words, a terror-management strategy designed to hold at bay our most existential fears – fears that are in no way peculiar to today.